Mechanisms for effecting fine and coarse adjustment

ABSTRACT

A mechanism for effecting fine and coarse adjustment in which a first member is mounted for movement relatively to a second member. The mechanism includes two substantially mutually perpendicular shafts which are geared together and which are rotatable relatively to each other to effect said movement.

United States Patent 11113,577,7

[72] Inventors Alexander John Munro [56] References Cited g T r C d E d UNITED STATES PATENTS my 508,390 11/1893 Linkletter 74/89.14 [21] Appl. No. 865,307

1,524,069 1/1925 Watkmson et al. 74/89.l4 [22] 2 306 723 12 1942 F] d 7 89 Patented May4l97l ora ay 4/ .14 [73] Assignee Vickers Limited FOREIGN PATENTS London, England 856,721 12/1960 Great Britain 74/89.14

Pn'mdry ExaminerFred C. Mattern, Jr. Assistant Examiner-Wesley S. Ratliff, Jr. 7 Attorney-Waters, Roditi, Schwartz & Nissen [54] MECHANISMS FOR EFFECTING FINE AND COABSE ADJUSTMENT ABSTRACT: A mechanism for effecting fine and coarse ad- 4 Claims, 1 Drawing Flg.

ustment 1n wh1ch a first member 15 mounted for movement [52] US. Cl 74/89.l4 relatively to a second member. The mechanism includes two [51] Int. Cl F16h 29/20 substantially mutually perpendicular shafts which are geared Field of Search 74/89. 14, together and which are rotatable relatively to each other to ef- 89.15, 424.8, 421, 425 fect said movement.

l5 /0 /3 x d M T 42 MECHANISMS FOR EFFECTING FINE AND COARSE ADJUSTMENT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to mechanisms for effecting fine and coarse adjustment and is more particularly but not exclusively concerned with mechanisms for effecting fine and coarse adjustment of microscopes.

SUMMARY OF THE INVENTION According to the present invention there is provided a mechanism in which a first member is mounted for movement relatively to a second member and incorporating a device for effecting said movement, said device comprising first and second, substantially mutually perpendicular, shafts mounted on said first and second members respectively for rotation relatively to each other, with said first shaft being mounted for axial displacement relatively to said second shaft and a geared connection between said shafts whereby rotation of said first shaft effects fine adjustment of said first member, and rotation of said second shaft effects a coarse adjustment of said first member by producing in each case, axial displacement of the first shaft. v

The geared connection between the first and second shafts may be constituted by a worm and wheel arrangement with the worm being formed on the first shaft and the worm wheel being formed on the second shaft.

In order to constrain the movement produced by the device, into a single path of adjustment, the members may be connected by parallel arms permitting bodily movement of the first member relatively to the second member. In this case the path traced by the moving system takes the form of a curve, so that for the teeth of the worm to remain in constant mesh with the teeth of the wheel, the worm is barrel-shaped with the pitch line of the worm teeth following a curve of a radius equal to that of the curved path traced by the connection point adjacent the first member of each arm. I

Preferably the arms form part of a flexure hinge system.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be more fully understood an embodiment in accordance therewith will now be described, by way of example, with reference to the accompanying drawing which shows diagrammatically and in elevation a mechanism for effecting fine and coarse adjustment of a first member relatively to a second member.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawing there is shown a mechanism in which a first member, generally indicated at l is mounted for movement relatively to a second member in the form of a fixed support bracket 2, the mechanism incorporating a device for effecting said movement including first and second substantially mutually perpendicular shafts 3 and 4 rotatably mounted in bearings in the first and second members respectively. The first and second shafts 3 and 4 are operable, for example manually, through control knobs 5 and 6 respectively and are geared together as indicated at 7, the geared connection 7 between the shafts 3 and 4 being such that rotation of wheel arrangement with the worm 8 being formed on the shaft 3 and the wheel 9 being formed on the shaft 4.

In the preferred embodiment of the invention illustrated in the drawing, the movement of the member 1 produced by rotation of either of the shafts 3 and 4 by their respective control knobs 5 and 6 is constrained into a single substantially verhinged parallelogram incorporating parallel arms IM and 10b interconnecting the members 1 and 2. As will be evident from the drawing the path of movement traced by any point on the flexure hinge system takes the form of a curve as indicated at 15 in broken lines.

Consequently 'the locus of any particle of the moving member 1 is a curve related to the centers of rotation of the flexure hinge system 10. Two positions of displacement of the system 10 by rotation of either of the shafts 3 and 4 are shown in broken lines on either side of an intennediate position shown in full lines.

As the shaft 3 is carried by the moving member 1, the locus of any point on the shaft 3 is a curve produced by the restraint of the flexure hinge system 10. Accordingly, in order thatthe teeth of the worm 8 are in constant mesh with the teeth of the wheel 9, during vertical movement of the member 1 with the shaft 3 the worm 8 is a barrel-shaped, as shown, so that the pitch line of the worm teeth follows a curve which is equal and opposite to that curve produced by the flexure hinge system 10 (i.e. the pitch line curve has a radius equal to that of the curved path traced by the connection points 11 and 12). Preferably, as shown, the worm teeth are formed by the cross section of a helical thread with the curved pitch line being substantially normal to the longitudinal axis of the shaft 3.

If the knob 6 is rotated through one complete turn the shaft 3 is moved axially along a curved path, the length of which i equals the length of the pitch circumference of the wheel 9, to effect coarse adjustment. In order to effect fine adjustment, the knob 5 is rotated, the wheel remaining stationary whilst axial displacement of the shaft 3 obtains. One complete rotation of the knob 5 results in the shaft 3 moving axially by one tooth of the worm 8. It should be mentioned that the design of the gearing is such that rotation of the wheel 9 by the knob 6 does not produce rotation of the shaft 3. Furthermore rotation of the knob 5 for fine adjustment does not produce rotation of the wheel 9. Thus coarse and fine adjustment of the first member 1 relatively to the second member 2 are effected by producing axial displacement of the first shaft 3.

Purely by way of example, if the wheel 9 has 20 teeth, then 20 turns of the knob 5 will be equivalent to one turn of the knob 6.

By the present invention is provided a mechanism for fine and coarse adjustment of a first member relatively to a second member, which has particular application to microscopes in which the first member is constituted by the moving assembly of the microscope and the second member 2 by the microscope support bracket.

We claim:

1. A mechanism for effecting fine and coarse adjustment in which a first member is mounted for movement relatively to a second member and incorporating a device for effecting said movement, said device comprising:

a. first and second, substantially mutually perpendicular,

shafts mounted on said first and second members respectively for rotation relatively to each other, with said first shaft being mounted for axial displacement relatively to said second shaft, and

b. a geared connection between said shafts whereby rotation of said first shaft effects a fine adjustment of said first member, and rotation of said second shaft effects a coarse adjustment of said first member by producing in each case, axial displacement of said first shaft.

2. A mechanism as set forth in claim 1, wherein said geared connection is constituted by a worm and wheel arrangement with the worm being formed on said first shaft and the worm wheel being formed on the second shaft.

3. A mechanism as set forth in claim 2, wherein said first and second members are connected by parallel arms permitting bodily movement of said first member relatively to said second member and the worm is barrel shaped with the worm teeth having a pitch line which follows a curve of a radius equal to that of a curved path traced by the connection point adjacent said first member of each arm.

4. A mechanism as set forth in claim 3, wherein the arms form part of a flexure hinge system. 

1. A mechanism for effecting fine and coarse adjustment in which a first member is mounted for movement relatively to a second member and incorporating a device for effecting said movement, said device comprising: a. first and second, substantially mutually perpendicular, shafts mounted on said first and second members respectively for rotation relatively to each other, with said first shaft being mounted for axial displacement relatively to said second shaft, and b. a geared connection between said shafts whereby rotation of said first shaft effects a fine adjustment of said first member, and rotation of said second shaft effects a coarse adjustment of said first member by producing in each case, axial displacement of said first shaft.
 2. A mechanism as set forth in claim 1, wherein said geared connection is constituted by a worm and wheel arrangement with the worm being formed on said first shaft and the worm wheel being formed on the second shaft.
 3. A mechanism as set forth in claim 2, wherein said first and second members are connected by parallel arms permitting bodily movement of said first member relatively to said second member and the worm is barrel shaped with the worm teeth having a pitch line which follows a curve of a radius equal to that of a curved path traced by the connection point adjacent said first member of each arm.
 4. A mechanism as set forth in claim 3, wherein the arms form part of a flexure hinge system. 